According to the present teachings, various embodiments of a printhead unit assembly can include a printhead unit, mounting and clamping assembly, and an interface assembly. For various embodiments of a printhead unit assembly of the present teachings, a printhead unit and a mounting and clamping assembly can provide for repeatable strain-free, positioning of a printhead unit in a printing system. In various embodiments of a printhead unit assembly of the present teachings, a printhead unit and an interface assembly can have features that enable the ready interchangeability of various printhead units with a printing system. The ready interchangeability providing strain-free, repeatable positioning of a printhead unit in a printing system enables flexibility in creating targeted thin film processes, as well as reliable high-throughput production printing.